KR101944871B1 - Steering position and torque sensor - Google Patents

Abstract

Disclosed is a sensor circuit for use with a rotating shaft assembly installed in a housing, the rotating shaft assembly having an input shaft, an output shaft, and a torsion bar connecting the input shaft to an output shaft. When the CR coil installed in the housing around the rotary shaft assembly is energized, an electromagnetic field is generated. An RX coil is mounted on the rotary shaft assembly and rotates together with the rotary shaft assembly and has an output connected to a power circuit that generates electrical energy when excited by an electromagnetic field in the first coil. The power circuit supplies power to the angle sensor which again transmits a signal indicative of the angle between the input shaft and the output shaft to the first coil.

Description

[0001] STEERING POSITION AND TORQUE SENSOR [0002]

This application claims priority to U.S. Provisional Patent Application 61 / 448,256, filed March 2, 2011, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to angular sensors, and more particularly to an angle sensor between an input shaft and an output shaft.

In a steering system of the kind used in automobiles, the steering system generally includes an input shaft connected to the steering wheel. The input shaft is connected to the output shaft via a torsion bar, and the output shaft is mechanically connected to the vehicle wheel via a link. Thus, as the steering wheel rotates, the car wheel rotates through the genital torsion bar, the output shaft, and the steering link.

In many situations, it is highly desirable to determine the angular deviation between the input shaft and the output shaft of the steering mechanism. The degree of angular deviation between the input shaft and the output shaft, i.e., the degree of angular deflection of the torsion bar, is used by the vehicle management system to determine steering wheel torque and the amount of assistance provided by power steering. For example, if the vehicle rotates when the vehicle is stopped or nearly stopped during a vehicle parking situation, a relatively large angular deviation generally occurs between the input shaft and the output shaft, thus requiring increased power assistance to turn the vehicle wheel. It is also rare that this deviation exceeds about 20 degrees.

In addition to the angular deviation between the input shaft and the output shaft of the steering, it is desirable to know the angular position of the vehicle wheel in many situations. Since the steering wheel can generally be rotated three to four times completely, it is necessary to continue counting the number of revolutions to determine the absolute angular position of the vehicle wheel.

A system capable of monitoring the angular deviation between the input shaft and the output shaft of the steering wheel has been known for some time. This system, previously known, generally uses a transducer to measure the angular torque between the steering input shaft and the output shaft. However, since the steering output shaft can only be rotated three or four times, it has been necessary to provide a long length of electric cable (usually a ribbon cable) inside the steering column in the case of the previously known device. Sufficient ribbon cables have been provided so that the ribbon cable is wound around the steering column 2 or 3 times to accommodate multiple turns of the steering wheel.

However, previously known methods have not been found to be completely satisfactory in use. For example, the electrical connector can become entangled after extended use, which can cause electrical connections between the cable and the angle sensor between the steering input shaft and the output shaft to be caught or even broken. If this happens, the overall operation of the torque sensor for the steering system is compromised.

Similarly, systems for providing an output signal indicative of the angular position of the vehicle wheel during multiple rotations of the steering wheel have been known for some time. However, the previously known system was found to be overly complex and expensive to build.

The present invention seeks to provide a torque sensor and a wheel position sensor that overcome the above-mentioned disadvantages of previously known devices.

Briefly, in the present invention, a combined transmitting and receiving coil is coaxially installed around a vehicle steering column, the vehicle steering column including an input shaft, an output shaft, and a torsion bar connecting the input shaft and the output shaft together. In addition, the transmitting and receiving coils do not move with respect to the vehicle and thus do not move with respect to the steering column.

Advantageously, the transceiver includes a PCB having a conductive trace forming a coiled loop coaxial with the steering column. An electronic circuit such as an ASIC is electrically connected to the transmission / reception coil. The transmission / reception coil is electrically connected to an engine control unit (ECU) that controls the overall operation of the vehicle.

A second floating PCB including both the RX coil and the receiving coil is coaxially mounted on the output shaft so as to rotate integrally with the second output shaft. The RX coil is circular. However, the receiving coil includes at least two receiving coils, and more preferably about eight, reversely wound receiving coils wound in opposite directions, and these coils are also arranged coaxially around the output shaft. Both the RX coil and the receiving coil are formed on the second PCB and the second PCB is connected to the output shaft so that the receiving coil and the RX coil rotate integrally with the output shaft. The RX coil and receive coil are also connected to an electronic circuit such as an ASIC, which is also mounted on the second PCB.

An electrically conductive multiple lobe coupler is installed on the input shaft on the receive coil on the negative type PCB attached to the output shaft. The angle between the coupler and the receiving coil indicates a torque angle between the input shaft and the output shaft.

In operation, the transmit and receive coils on the fixed PCB are energized at high frequencies, such as 2-4 MHz. The electromagnetic energy generated by the transmit and receive coils energizes the RX coil on the negative type PCB, which powers the circuit on the negative type PCB. The negative type PCB also includes a circuit such as an ASIC that determines the angular position between the input and output axes depending on the voltage of the receive coil.

And the second circuit generates a digital output signal at a specified baud rate that is modulated at the same frequency as the transmit frequency at the transmit and receive coil on the fixed PCB. The circuit on the fixed PCB demodulates the signal from the negative PCB to provide the desired information to the vehicle ECU.

The torque sensor, i.e. the angle between the input shaft and the output shaft, is preferably detected by an inductive sensor, but other types of sensors, such as a Hall sensor, can alternatively be used.

Since the circuit on the negative type PCB is fully powered by the electromagnetic transfer from the fixed PCB and the data is communicated by the electromagnetic transfer between the fixed PCB and the negative type PCB, The requirement for an additional long electrical connector is completely avoided. Instead, only the electrical connections used in the present invention are electrical connections from the stationary PCB.

To determine the actual angular position of the wheel, the first gear wheel is preferably provided on its input or output shaft so as to rotate integrally with the input or output shaft. The gear wheel is engaged with the second gear wheel having a different number of teeth. Thus, the first and second gear wheels rotate at different rotational speeds.

A position sensor is associated with each gear wheel so that the angular position of the two gear wheels can be determined at any time. However, since the gear wheels rotate at different rotational speeds, the actual angular position of the first gear wheel and the angular position of the vehicle wheel can be accurately determined by the sensors up to a plurality of rotations of the steering input shaft and the output shaft.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood from the following detailed description taken in conjunction with the accompanying drawings, in which like reference numerals designate like parts throughout the several views.

1 is a side view showing a preferred embodiment of the present invention.
2 is an elevational view of a preferred embodiment of the present invention.
Figure 3 is an exploded view of a preferred embodiment.
4 is a block diagram showing the operation of the present invention.
5 is a schematic diagram showing the operation of the present invention.
6 is a schematic diagram showing a preferred embodiment of the modulation circuit.
8 is an elevational view showing a portion of a preferred embodiment of the wheel position sensor;
9 is a graph showing the operation of the wheel position sensor.
10 is a graph showing a signal received from a negative type PCB by a fixed PCB with respect to a digital signal;
11 is a graph showing signals received from a negative type PCB by a fixed PCB for an analog signal.

Referring to Figures 1-3, there is shown a steering column 10 of the kind used in a motor vehicle. The steering column 10 includes an input shaft 12 mechanically connected to the steering wheel 14 and an output shaft 16 mechanically connected to the vehicle wheel by a link (not shown).

The input shaft 12 and the output shaft 16 are coaxially aligned with each other and are mechanically connected together by a torsion bar 18. The torsion bar 18 allows the input shaft 12 to rotate slightly with respect to the output shaft 16 in accordance with the amount of torque applied to the steering wheel 14. [ However, the amount of rotation of the input shaft 12 with respect to the output shaft 16 is relatively small, generally 20 degrees or less.

Referring still to Figures 1-3, a fixed printed circuit board (PCB) 20 is preferably coaxially mounted about the steering column 12 adjacent one end of the torsion bar 18. In addition, the stationary PCB 20 is fixed with respect to the vehicle itself and therefore does not move with respect to the steering column 10.

A circular transmission and reception CR coil 22 is formed on the fixed printed circuit board 20 coaxially with the steering column 10. [ The CR coil 22 is connected to an electronic circuit 24 such as an ASIC and the electronic circuit is electrically connected to the vehicle electronic control unit 28 by a cable 26.

1 to 3, the negative type PCB 30 is connected to its output shaft 16 so as to be able to rotate integrally with the output shaft 16. A circularly wrapped RX coil 32 is formed of conductive traces on a PCB plate that are positioned on the sub-type PCB 30 when the CR coil 22 on the stationary PCB 20 is activated. And is in a position to be inductively coupled with the RX coil 32. Preferably, the coils 22, 32 are coaxially aligned with one another. A receiving coil 34 having at least two loops 36 (Fig. 2) wound in the opposite direction is also formed as a conductive trace on the negative type PCB 30. Fig.

And the electric conductive coupler 38 is attached to the input shaft 12 so as to rotate integrally with the input shaft 12. [ The coupler 38 may also be any of several shapes such as a multi lobe shape as shown in FIG. Since the coupler 38 is attached to the input shaft 12 and the negative type PCB 30 is attached to the output shaft 16, the relative angle between the coupler 38 and the negative type PCB 30 And is proportional to the amount of applied torque.

Referring now to FIGS. 1-4, the ASIC 24 on the fixed PCB 20 includes an oscillator 50 that oscillates at high frequencies, such as 2-4 MHz. This oscillator 50 is electrically connected to the CR coil 22 on the fixed PCB 20 to excite the coil.

The signal generated by the CR coil 22 is inductively coupled to the RX coil 32 on the negative type PCB 30. [ The RX coil 32 is also electrically coupled to an ASIC 52 that transmits electromagnetic radiation from the CR coil 22 to the ASIC 52 on the negative PCB 30, To a power sufficient to supply power. Thus, an external power line for supplying power to the second ASIC 52 is not required.

The receiving coil 36 on the negative type PCB 30 is also electrically connected to the second ASIC 52 as an input signal. Because the receive coil includes an even number of loops 36 (FIG. 3) wound in opposite directions, the voltage at the receive coil 36 is dependent on the rotational position of the coupler 38 relative to the negative PCB 30 . For example, a zero voltage at the receiving coil 32 indicates that there is no bias between the input shaft 12 and the output shaft 16 of the steering column 10, and a positive voltage is applied between the input shaft 12 and the output shaft 16 And the negative voltage indicates that there is a torque in the opposite rotational direction between the input shaft 12 and the output shaft 16. [

5, there is shown a configuration, i.e., a Jordi Sacristan-Riquelme system, for delivering electromagnetic radiation from a CR coil 22 on a fixed PCB 20 to power a second ASIC 52 . Even if the circuit shown in FIG. 4 is self explanatory, the oscillator in the first ASIC 24 will energize the LC circuit at the resonant frequency to generate electromagnetic radiation. The electromagnetic radiation is detected by the LC circuit comprising the RX coil 32 and supplies power to the second ASIC 52.

Referring now to FIG. 6, the second ASIC 52 is programmed to generate a fixed digital signal given to the fixed PCB 20 at a predetermined baud rate (e.g., 50,000 Hz). For example, as shown in FIG. 6, the power generated in the power circuit shown in FIG. 4 is connected at the port 60 to supply power to the modulation circuit 62. The switch 64 is opened and closed at the same frequency as the oscillator 50 to selectively supply power to the RC network. However, the data input port 66 controls the second switch 68 at a modulating frequency (e.g., 50K) to selectively ground the capacitor Cmod in the RC network. Thus, there is a change in the amplitude of the transmission / reception CR coil 22 on the fixed PCB 20.

As shown in FIG. 10, when the output of the ASIC 2 is in the digital format, the data is sent back to the fixed PCB in the same manner as the RFID. A sequence of binary data is encoded with a waveform according to IEEE 802.3, where the rising edge indicates "1" and the falling edge indicates "0". The waveform is then amplitude modulated through the circuit shown in FIG. 6 into a signal. ASIC1 decodes the data in reverse order, i. E. Using the circuit shown in Fig. 7, to demodulate the signal into an encoded waveform, and then decodes the waveform into a binary data sequence.

As shown in FIG. 11, when the output of the ASIC 2 is in the analog form, the result is first converted to a PWM waveform, where the duty cycle (td / tp shown in the figure) represents the twist angle. A duty cycle of 50% indicates that there is no twist angle between the input shaft and the output shaft. A duty cycle of less than 50% indicates that there is a torsion angle in one direction, and a duty cycle greater than 50% indicates that there is a torsion angle in the other direction. The PWM waveform is amplitude-modulated through the circuit shown in FIG. The ASIC 1 demodulates the signal using the circuit shown in FIG. 7 for further signal processing to produce a PWM waveform.

The circuit may include a processor programmed to output the magnitude and direction of the angle between the input and output axes.

7, the ASIC 24 on the fixed PCB plate receives a signal on the CR coil 22 via an attenuator 70 and outputs the signal as a data output signal on line 26 to a bandpass filter 72 And an amplifier 74 connected to the ECU 28.

Both the torque sensor and the angular sensor on the first gear wheel can share the same transmitter and the same conductive coupler when using the inductive sensor. With this configuration, parts can be saved and the possible interference between the two sensors can be completely eliminated.

As can be seen from the foregoing, the present invention provides an effective torque sensor for two rotary elements that are connected together by a torsion bar, such as a steering column in a motor vehicle. The use of external wiring to supply power to the ASIC 52 on the negative type PCB 30 is unnecessary because the rotating portion of the sensor, the negative type PCB, is fully powered by incident radiation coming from the fixed PCB 20 .

Further, although the sensor for the relative angle between the input shaft 12 and the output shaft 16 is described as an inductive sensor, other sensors may be used without departing from the gist of the present invention. For example, the Hall effect sensor may alternatively be used to detect the angle between the input shaft 12 and the output shaft 16. Other types of sensors may alternatively be used.

Referring now to FIG. 8, in many applications, such as automotive steering columns, the output shaft 16 can rotate at a high number of revolutions. In order to determine the actual angular position of the vehicle wheel, it is necessary to know the instantaneous angular position of the output shaft 16 from a known position as well as the rotation of its output shaft 16.

The first pinion 80 is attached to the output shaft 16 (or the input shaft 12) so as to rotate integrally with the output shaft 16 to determine the number of revolutions of the output shaft 16. [ The pinion 80 also has a known number of teeth.

The first pinion 80 engages with a second pinion 82 which is rotatable about a fixed axis in the vehicle. However, the second pinion 82 has a different number of teeth than the first pinion 80, and the pinions 80 and 82 rotate at different rotational speeds.

As best seen in FIG. 9, the actual angular position of the two pinions 80, 82 is shown for a plurality of rotations, e.g., four rotations. 8, the actual angular positions of the two pinions 80 and 82 are the same only at a predetermined full revolution of the output shaft 16. [

A sensor 84, which may be any type of conventional sensor, is operatively connected to both pinions 80 and 82 to determine the rotational position of the two pinions 80 and 82 at any time. Given the position of the two pinions 80 and 82 at any time, the actual rotational position and number of rotations of the output shaft 16 can be determined from the diagram shown in FIG. 8 as programmed by the appropriate processor.

Thus, with the torque sensor shown in Figures 1-6 and the position shown in Figures 7 and 8, all desired information from the steering system of the vehicle can be determined for use in the engine ECU.

Having described the invention, many modifications to the invention will become apparent to those skilled in the art without departing from the spirit or scope of the appended claims.

Claims (10)

The sensor circuit comprising an input shaft, an output shaft, and a torsion bar connecting the input shaft to an output shaft, the sensor circuit comprising an output signal indicative of an angle between the input shaft and the output shaft, Lt; / RTI >
The sensor circuit includes:
A CR coil disposed in the housing and annularly disposed around the rotary shaft assembly and generating an electromagnetic field excited by a frequency source,
And an RX coil provided around one of the input shaft and the output shaft. When the RX coil is excited by an electromagnetic field from the CR coil, the RX coil connected to the power circuit generating only power from the ON electromagnetic field in the CR coil coil,
An angle sensor which is installed in one of the input shaft and the output shaft and generates a radio output signal indicative of an angle between the input shaft and the output shaft to the CR coil,
A sensor output circuit receiving the output signal from the CR coil and generating a sensor signal indicative of an angle between the input shaft and the output shaft,
A driving pinion fixed to the rotary shaft assembly so as to rotate together with the rotary shaft assembly, a driven pinion rotatably installed in the housing, and a coefficient circuit for generating a counter signal indicative of the rotational speed and rotational direction of the driven pinion Including sensor circuit. The method according to claim 1,
Wherein the angle sensor comprises:
A receiving coil disposed around the one of the input shaft and the output shaft, the receiving coil having at least two loops wound in opposite directions to each other,
An electrically conductive coupler having a number of lobes equal to the number of loops wound opposite to each other in the receiving coil and provided on the other of the input shaft and the output shaft,
And an output circuit that is installed in the one of the input shaft and the output shaft and receives power supply by the power circuit,
The electrically conductive coupler is on the receive coil such that the voltage output from the receive coil varies with the angular position of the coupler relative to its receive coil,
Wherein the output circuit receives the voltage signal at the receiving coil as an input signal and generates the sensor signal indicative of the angle between the input shaft and the output shaft to the CR coil. 3. The method of claim 2,
Wherein the CR coil comprises a conductive trace on a printed circuit board. 3. The method of claim 2,
Wherein the RX coil comprises a conductive trace on a printed circuit board. 3. The method of claim 2,
The sensor receiving coil includes a conductive trace on a printed circuit board. 3. The method of claim 2,
Wherein the RX coil and the receive coil both comprise conductive traces on a printed circuit board. 3. The method of claim 2,
Wherein the coupler is mounted on an input shaft. 3. The method of claim 2,
Wherein the RX coil and the receiver coil both include conductive traces on a printed circuit board mounted on the output shaft. 3. The sensor circuit according to claim 2, wherein a frequency of the output signal varies depending on an angular position between an input shaft and an output shaft. delete

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